1. Field of the Invention
The present invention relates to a buckle used as a clasp fastener for belts, suspenders for trousers, or straps on bags.
2. Description of the Prior Art
One prior buckle shown in Japanese Utility Model Laid-open Publication No. 2-19304 comprises a male member and a female member that are releasably coupled together to connect loose ends of a belt. The male member includes a pair of hook-like locking members. The female member includes a pair of actuating members each having a hook-like retaining portion. The actuating members are slidably mounted and linearly reciprocate toward and away from each other. A pair of coil springs urges the actuating members, respectively, in a direction away from each other. The sliding direction of the actuating members is restricted by guide portions which are formed by a pair of interior side surfaces of the female member. The female member further has a pair of stopper portions engageable with respective one end portions of the actuating members to retain the forces of the coil springs exerted on the actuating members.
To engage the buckle, the male member is inserted into the female member until the locking members are latched by the corresponding retaining portions. In this instance, since the actuating members are urged in a direction away from each other by the forces of the coil springs, the locking members are interlocked with the retaining portions. To disengage the buckle, the actuating members are forced inwardly toward each other against the forces of the coil springs until the locking members are released from the retaining portions. The male member is thus allowed to be detached from the female member. Then, the male member is pulled out from the female member to disengage the buckle.
In Japanese Utility Model Laid-open Publication No. 61-202212 corresponding to U.S. Pat. No. 4,672,725 granted Jun. 16, 1987 to Kasai, there is disclosed another prior buckle which is composed of a male member having a pair of resiliently deformable legs, and a female member having a pair of fixed retaining portions. The legs are interlocked with the retaining portions to couple together the male and female members. Thus, the legs serve as locking members. When the male and female members are to be disengaged, two confronting presser portions of the female member are pressed toward each other to resiliently deform or flex the front ends of the legs inwardly until the legs are released from the retaining portions. The male and female members are then pulled apart to disengage the buckle.
Still another prior buckle shown in Japanese Utility Model Laid-open Publication No. 2-33614 includes a female member having a pair of pivotally movable actuating members each provided with a retaining portion. The retaining portions of the respective actuating members are engageable with a pair of locking members of a male member, respectively, to couple the male and female members. When the male and female members are to be disengaged, the actuating members are pivoted in one direction to release the locking members from the retaining portions. The actuating members are urged in the opposite direction by a resilient member. In order to limit the angular movement of the actuating members toward the opposite direction, the female member includes a pair of stopper portions which are engageable with the actuating members, respectively.
In the prior buckle shown in the first-mentioned Japanese publication, the forces of the coil springs act only in a direction parallel to the direction of movement of the actuating members. As a result, due to a play resulting from the working tolerance between the locking members and the retaining portions, the male and female members being coupled together tend to wobble particularly in a direction perpendicular to the direction of movement of the actuating members. The play, however, cannot be practically dispensed with and is indispensable to facilitate a smooth and reliable engagement between the male and female members. In addition, when the buckle is to be disengaged, the male member is pulled out from the female member with one hand of the user while the actuating members are being pressed by the other hand. Thus, both hands of the user are occupied when the buckle is disengaged. Furthermore, the forces of the coil springs, which act in a direction parallel to the direction of movement of the actuating members, are born by the stopper portions which retain respectively thereon one end portions of the actuating members. With this construction, each of the actuating members, as it is manipulated, produces a moment of force or torque which will increase a friction between the actuating member and the corresponding guide portion. Because of the increased friction, sliding surfaces and a coating layer, if any, are worn off irregularly. In addition, the movement of the actuating members becomes sluggish and, hence, smooth attaching and detaching operations of the buckle are difficult to achieve. Furthermore, it occurs likely that the actuating members and the coil springs are assembled in an unstable condition. The thus assembled actuating members are likely to tilt while the buckle is in use.
In the prior buckle disclosed in the second-mentioned Japanese publication, the resilient legs of the male member must be long enough to possess a certain degree of resiliency. The male member having such resilient legs is relatively large in size and enlarges the overall size of the buckle particularly in the longitudinal direction of the legs. In addition, since the legs and the retaining portions are not interlocked resiliently, the male and female members are permitted to cause wobbling. When the buckle is to be disengaged, the presser portions are compressed to resiliently flex the legs toward each until the legs are released from interlocking engagement with the retaining portions. When released, the legs tend to thrust out from the female member due to the resilient forces stored in the legs. In this instance, however, since the retaining portions extend in a direction perpendicular to the acting directions of the resilient forces, a certain muscle effort is needed in order to separate the male and female member against a friction between the legs and the retaining portions. In practice, the male member is pulled out from the female member by one hand of the user while the presser portions are being compressed by the opposite hand.
In the prior buckle shown in the last-mentioned Japanese publication, each of the actuating members is pivoted at one end thereof. There is no means provided for guiding the corresponding actuating member as it undertake a pivotal motion. Accordingly, the actuating members are unstable in operation. In addition, the female member includes a base plate and a cover plate attached together, with the actuating members and the resilient member held between the base and cover plates. When assembling the female member, the actuating members and the resilient member are placed on the base plate. In this instance, however, due to the resilient force acting on the actuating members, the actuating members are the resilient member are likely to displace and sometimes detached from the base plate before the cover plate is attached to the base plate.